at first I tried with a couple of crypts, some java fern, a couple of vallis gigantea and some anubias nana. the crypts just melted, the java fern got eaten as did all the new growths of the vallis and new anubias leaves. I was left with 5' long vallis leaves trailing the full length of the tank and a bit round the corner!
The cichlids just dug up the roots all the time, the only success I had was to plant the vallis into small terracota pots filled with laterite and gravel. substrate in the tank was sand.
I still ended up with laterite and roots all over the substrate after their digging. Not worth the effort.
Currently I have a piece of simulated bogwood and I'm persisting with trying to establish java moss and anubias nana on it. Like Mana says, I just need some kind of greenery in there. the fish also seem to like it, sometimes to feed in (and on!), sometimes for cover.